MERCURY-GLASS INTERACTIONS IN FLUORESCENT LAMPS

During the operation of a fluorescent lamp mercury chemically combines with various components inside the lamp. For some types of lamps most of the bound mercury is observed to reside in the glass, despite the intervening phosphor layer. This consumption of mercury by the glass only occurs when a mercury/rare-gas plasma is present. Experiments were performed to isolate the various factors arising from the operation of the plasma in order to determine which ones are important in driving mercury consumption in the glass. These experiments include shielding samples from the plasma, measuring the line-of-sight transmission of the phosphor, and applying small radial de Electrical biases to the lamp. In addition, various analytical techniques, including x-ray photoelectron spectroscopy, Rutherford backscattering, scanning electron microscopy, and thermally stimulated evolution where used to study the glass surface after exposure to a mercury/rare-gas plasma. From these studies it is postulated that electrochemical effects play a major role in binding mercury to the glass.